(12) United States Patent
`(10) Patent N0.:
`US 6,891,820 B1
`
`Pham et al.
`(45) Date of Patent:
`May 10, 2005
`
`USOO6891820B1
`
`(54) UTILIZATION OF THE INTERNET
`PROTOCOL TO FACILITATE
`
`................ 370/331
`6,473,413 B1 * 10/2002 Chiou et a1.
`6,574,266 B1 *
`6/2003 Haartsen ..................... 375/133
`
`COMMUNICATION INVOLVING MOBILE
`DEVICES
`
`(75)
`
`Inventors: Hiep Pham, San Diego, CA (US);
`Martin Morris, San Diego, CA (US);
`Rajiv Kumar, San Diego, CA (US);
`Lyn Nguyen, San Diego, CA (US)
`
`(73) Assignee: Broadcom Corporation, Irvine, CA
`(US)
`Subject to any disclaimer the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`( *) Notice'
`
`(22)
`
`Filed:
`
`Jul. 6, 1999
`
`(51)
`Int. Cl.7 .................................................. H04Q 7/24
`
`(52) US. Cl. ....................... 370/338; 370/401
`(58) Field of Search .............................. 370/310, 310.2,
`370/328—338, 351—3, 389—402, 431—437,
`445, 403—409, 475, 395.2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,490,139 A *
`5,572,528 A
`5,636,216 A
`
`2/1996 Baker et a1.
`11/1996 Shuen
`6/1997 Fox et 211.
`
`................ 370/312
`
`.............. 126/25 R
`
`7/1997 Sharony
`5,652,751 A
`5,678,531 A * 10/1997 Byers et a1.
`5,696,903 A
`12/1997 Mahany
`5,699,353 A
`12/1997 Kent
`5,708,655 A
`1/1998 Toth et a1.
`5,742,598 A
`4/1998 Dunn et a1.
`5,754,547 A
`5/1998 NakaZaWfi
`57812531 A
`9/1998 016111.18 6t a1~
`3923:9323 2
`117199: SDtObelS et al‘
`,
`,
`ewar
`5,845,081 A
`12/1998 Rangarajan et a1.
`5,850,592 A
`12/1998 Ramanathan
`5,854,899 A
`12/1998 Callon et a1.
`
`EP
`EP
`W0
`
`FOREIGN PATENT DOCUMENTS
`0695059 A1
`1/1996
`A—0 695 059
`1/1996
`W0 99/14897
`3/1999
`
`OTHER PUBLICATIONS
`Geneseo.edu—website:
`“PMDF
`System Manager’s
`Guide—PMDF—REF—5.1; Overview of PMDF” (pp. 1 of 1,
`1 of 2 and 2 of 2) (not included).
`Haartsen, Jaap, “Bluetooth—the universal radio interface
`for ad hoc, wireless connectivity”, Ericsson Review, Se,
`Ericsson (3) 2110—117, (1998).
`Haartsen, Jaap, “Bluetooth—The universal radio interface for
`ad hoc, wireless connectivity,” Ericsson Review, No. 3, pp.
`
`“Specification of the Bluetooth System, Core, Version
`1.0B,” Bluetooth SIG Specifications, pp. 18—42, (Dec. 1,
`1999)
`
`(Continued)
`
`Primary Examiner—David Vincent
`(74) Attorney, Agent, or Firm—McAndrews, Held &
`Malloy, Ltd.
`
`(57)
`
`ABSTRACT
`
`.
`.
`.
`A data communication system capable of forwarding
`IP-addressed data to devices as such devices move among
`networks having different IP addresses is disclosed herein.
`~
`~
`~
`The system includes first and second networks containing
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`plurality of nodes is adapted to receive data transmiss10ns
`from an external IP-based network. Upon Joming the first
`network, this device is assigned an IP address which remains
`with it irrespective of whether it moves beyond the range of
`the first network. When this device roams into the vicinity of
`the second network, data addressed to the device which is
`received at the first network is forwarded via at least one
`-
`node of the second network to the deVice.
`
`16 Claims, 3 Drawing Sheets
`
`12
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`20\ ® \
`
`
`
`D2
`~‘
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`
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`10
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`1
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`APPLE 1039
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`APPLE 1039
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`1
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`

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`US 6,891,820 B1
`Page 2
`
`OTHER PUBLICATIONS
`Bluetooth Adopter’s website: “Specification of the Blue-
`tooth System” v.0.8 Jan. 22, 1999 (pp. 1—224).
`Genese0.edu—Website: “PMDF System Manger’s Guide—
`PMD—REF—S .1; Overview of PMDF” (pp. 1 0f 1; 1 0f 2 and
`2 0f 2).
`
`Haartsen, Jaap, “Bluetooth—The universal radio interface for
`ad hoc, Wireless c0nnect1v1ty, Erlcsson Revzew, NO' 3’ pp.
`110—111 (1998)
`
`* cited by examiner
`
`2
`
`

`

`US. Patent
`
`May 10, 2005
`
`Sheet 1 0f 3
`
`US 6,891,820 B1
`
`FIG.1
`
`D2
`
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`3
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`

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`US. Patent
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`May 10, 2005
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`Sheet 2 0f 3
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`US 6,891,820 B1
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`a—Q_
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`4
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`US. Patent
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`May 10, 2005
`
`Sheet 3 0f3
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`US 6,891,820 B1
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`
`
`RF
`106
`
`Transceiverm
`
`
`
`RF
`5
`f Transceiver #2
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`100
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`Adapter
`Card #1
`
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`Adapter
`Card or
`
`Modem
`
`To/From
`“mad
`LAN
`or
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`
`
`
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`
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`Updating Routine
`Routine
`L35:
`m :
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`:
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`
`5
`
`

`

`US 6,891,820 B1
`
`1
`UTILIZATION OF THE INTERNET
`PROTOCOL TO FACILITATE
`COMMUNICATION INVOLVING MOBILE
`DEVICES
`
`CROSS REFERENCE TO RELATED PATENT
`APPLICATIONS
`
`The entire disclosures of copending US. Patent Applica-
`tion entitled “Distributed Management of an Extended Net-
`work Containing Short-Range Wireless Links” and copend-
`ing US. Patent Application entitled “Implementation of
`Power Control in a Wireless Overlay Network”, both filed
`on even date herewith, are hereby incorporated by reference.
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to communication
`systems, and more particularly to a method and associated
`apparatus for allowing a device to continue communication
`via the Internet Protocol (“IP”) even while moving among
`networks having different associated IP addresses.
`
`BACKGROUND OF THE INVENTION
`
`Computer networks allow multiple computers, peripher-
`als and other information storage, retrieval or processing
`devices to share data. Each device attached to a network is
`
`typically referred to as a node on the network, or a node that
`is part of the network. Local Area Networks (“LANs”) have
`historically consisted of nodes interconnected by physical
`telecommunications media (e.g., coaxial cable, twisted pair
`wire, or fiber optics). Recently wireless LANS, the nodes of
`which are not connected by means of a physical medium,
`have started to appear in the market. These wireless LANs
`communicate by means of infra-red (IR), radio or other
`signals. One of the benefits of using wireless LANs is that
`cabling is not required. This is a particularly useful feature
`for mobile nodes such as laptop and notebook computers,
`PDAs (personal digital assistants), and the like. If equipped
`with an appropriate wireless adapter, the mobile nodes can
`move around within a predefined coverage area and remain
`connected to the network.
`
`In order for the nodes of a particular network to be able
`to communicate with each other, some sort of common
`addressing scheme must be implemented. In a traditional
`wired network, one very common method of communicating
`between nodes is to utilize Internet Protocol (“IP”) address-
`ing. When a node initially joins a network operating with the
`Internet Protocol, it is assigned an IP address consisting of
`at least two portions: a network address and a destination
`address. IP addresses are typically fixed and remain with the
`node irrespective of whether the node relocates to another
`network. In a traditional wired network, the fixed nature of
`IP addresses is not problematic because nodes are stationary
`and consequently do not migrate to networks outside of their
`original home network. Recently, wireless nodes have been
`added to traditionally hard-wired networks. Like all devices
`adhering to the Internet Protocol, mobile devices are
`accorded IP addresses having a network portion and a device
`portion. The network portion identifies the mobile device’s
`“home network” while the device portion distinguishes the
`mobile device from other members of its home network. The
`
`routing of data packets through the Internet is generally
`exclusively based upon the network portion of the destina-
`tion IP address. Specifically, Internet routers extract
`the
`destination network address from a given data packet and
`then forward that packet to the appropriate network. Once
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`the network
`the packet reaches the appropriate network,
`server examines the device portion of the IP address and
`forwards the packet to the appropriate device.
`When a mobile device is located in its home network, data
`packets addressed to a particular mobile device are simply
`sent to such device upon being received at the home net-
`work’s access point. This process is transparent to the user
`so long as the mobile unit is located within range of its home
`network. However, when the mobile device travels outside
`of its home network data packets cannot easily be forwarded
`thereto and are often “dropped”, which results in loss of
`data.
`
`Several methods have been proposed to allow mobile
`devices to continue. IP-based communication even when
`
`moving between networks having different IP addresses.
`One such technique requires that the mobile unit report
`changes in its address to the access point or network
`manager in its home network. A router located in its home
`network stores each new IP address for the mobile unit and
`
`forwards any incoming packets to the mobile device’s new
`IP address. An alternate approach involves establishing a
`pseudo presence, also called a “spoofed address,” at the
`mobile’s home network location. However, when mobile
`devices frequently move between networks having different
`IP addresses, these address-mapping and forwarding tech-
`niques can result in packets being forwarded to multiple
`locations, which may cause confusion and loss of data
`
`SUMMARY OF THE INVENTION
`
`Briefly, therefore, the present invention relates to a data
`communication system capable of forwarding IP-addressed
`data to devices as such devices move among networks
`having different IP addresses. The present invention includes
`first and second networks containing first and second plu-
`ralities of nodes. At least one of the first plurality of nodes
`is adapted to receive data transmissions from an external
`IP-based network. Upon joining the first network,
`this
`device is assigned an IP address which remains with it
`irrespective of whether it moves beyond the range of the first
`network (i.e.,
`the device’s “home” network). When this
`device roams into the vicinity of the second network, data
`addressed to the device which is received at the first network
`is forwarded via at least one node of the second network to
`
`the roaming device.
`In a preferred embodiment, each of the nodes in the first
`and second networks broadcast messages indicating the
`services that it offers and the nodes that are within its range.
`These broadcasts allow the mobile device to determine
`which devices it can use to create a connection between
`
`itself and the local access point in its home network. When
`the mobile device moves beyond its home network,
`it
`reestablishes a connection to its local access point using
`whatever combination of nodes it deems as being most
`efficient. Once this connection is made,
`the local access
`point is able to forward data to the mobile device.
`In an alternate embodiment, an internetworking node
`participates in both the first and second networks, and
`receives a first set of network information relating to the first
`network from the first plurality of nodes. In an another
`embodiment, the mobile device is capable of anticipating
`when it is about to lose contact with one of the nodes that is
`
`providing a connection between it and its home local access
`point. When the mobile device makes this determination, it
`attempts to establish an alternative route for the connection
`to its local access point. If the mobile device is of a type
`requiring continuous connection to an external network, an
`
`6
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`

`

`US 6,891,820 B1
`
`3
`additional embodiment allows the mobile device to simul-
`
`taneously maintain more than one connection between itself
`and its local access point. This minimizes the risk that data
`packets addressed to the mobile device will be “dropped”.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the accompanying drawings:
`FIG. 1 shows a data communication system comprising
`two wireless networks and a means for forwarding data
`between the networks.
`
`FIG. 2 contains a data communication system consisting
`of two wireless networks and an internetworking node in
`accordance with a preferred embodiment of the present
`invention.
`
`FIG. 3 is a block diagram illustratively representing the
`components of a wireless node and associated software
`configured in accordance with a preferred embodiment of
`the present invention.
`
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`DETAILED DESCRIPTION OF THE
`INVENTION
`
`The present invention is more fully described with refer-
`ence to FIGS. 1—3. An exemplary implementation of the
`invention is discussed and illustrated with reference to its
`
`25
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`implementation using wireless networks predicated on the
`proposed “Bluetooth” wireless communications protocol.
`This protocol contemplates the grouping of physically proxi-
`mate wireless nodes, and is described in Specification of the
`Bluetooth System, v0.8, Jan. 22, 1999 (and in subsequent
`revisions thereof). It should be understood that this inven-
`tion is not limited to such a wireless protocol, and could be
`similarly implemented using other types of fixed or wireless
`networks. As is described hereinafter, the present invention
`discloses a method and apparatus for relaying data addressed
`to a mobile device nominally associated with a first network
`when such device becomes associated with other networks.
`
`FIG. 1 illustrates a data communication system 10 con-
`sisting of a hard-wired network 12 and first and second
`wireless networks 20 and 22 containing network nodes A1
`and A2 respectively. The first and second wireless networks
`20 and 22 each contain a plurality of wireless nodes. For
`purposes of clarity, only wireless nodes L1 and L3 are
`depicted in wireless networks 20 and 22. It should nonethe-
`less be understood that
`the present invention is equally
`applicable to implementations in which first and second
`wireless networks include numerous wireless nodes. The
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`system 10 also contains a relay node L2 connecting the two
`wireless networks, a first mobile device D1, and a hard-
`wired device D2 connected to the hard-wired network 12. In
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`50
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`a typical configuration, D2 would actually be a network of
`devices rather than a single device. The device D2 may
`comprise either a network of devices or simply a single
`device. Since the actual number of devices represented by
`D2 is irrelevant for purposes of explanation of the present
`invention, device D2 will hereinafter be referred to as a
`single device.
`For purposes of illustration, it is assumed that certain of
`the wireless nodes depicted in FIG. 1 are mobile relative to
`one another. In the network architecture of FIG. 1, each node
`within the first network 20 is within the wireless coverage
`area of network access node A1 and each node within the
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`second network 22 is within the wireless coverage area of
`network access node A2. The network access nodes A1 and
`A2 serve as conduits to the external network 12 for the first
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`65
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`and second wireless networks 20 and 22, respectively. The
`
`4
`access nodes A1 and A2, as well as a relay node L2, are also
`disposed for wireless communication with the nodes L1 and
`L3.
`Because the nodes within the wireless networks 20 and 22
`
`are not necessarily within transmission range of all the other
`wireless nodes within the same networks, each wireless
`node may not be able to monitor all of the traffic within its
`network. For example, wireless node L1 may be able to
`“listen” to wireless node L2 but may not be able to monitor
`transmissions from wireless node L3. In a preferred imple-
`mentation each wireless node transmits an advertisement
`
`identifying its address and the services it offers. Each such
`advertisement also incorporates the address of all other
`wireless nodes from which advertisements are received by
`the node transmitting a given advertisement. Based on this
`information, the mobile device D1 can determine all nodes
`participating in the networks and the service offered by each.
`As used herein the term “services” encompasses, without
`limitation, the capability of a given node to relay message
`information to and from one or more outside networks.
`
`Accordingly, the advertisement issued by each wireless node
`may also identify the other networks within which the
`wireless node is capable of communication and the services
`offered by each.
`Referring to FIG. 1, when D1 first seeks to join the first
`wireless network 20 it transmits a signal to the network
`access node A1 via wireless node L1 so that
`it can be
`
`assigned an IP address by the Internet Service Provider
`(“ISP”) providing network access via node A1. Through this
`transmission, device D1 establishes the first wireless net-
`work 20 as its home network;
`that is,
`it designates the
`network address of the first wireless network 20 as its
`network address. Because device D1 is not hard-wired to
`
`node A1, it is necessary for device D1 to access node A1 via
`a wireless communication link. In the exemplary implemen-
`tation of FIG. 1, device D1 determines that it can establish
`a connection to node A1 through node L1 by listening to the
`periodic advertisements issued by nodes A1 and L1. As was
`mentioned above, these broadcasts contain network connec-
`tivity information pertinent to of all of the devices within
`range of A1 and L1. For example, A1’s broadcast would
`indicate that it is connected to the hard-wired network 12,
`and is capable of communication with nodes L1 and L2.
`Similarly, node L1’s broadcast would reveal that it is within
`range of, and capable of communication with, nodes A1, L2
`and D1.
`
`Data may be routed to node D1 in a conventional manner
`when node D1 is within its home network 20. In this
`situation data destined for node D1 is sent to the IP address
`of node A1 from the external network 12. On the basis of the
`
`advertisements broadcast by L1, node A1 determines that
`node L1 has established a connection to D1. Node A1 then
`sends the data received from the external network 12 to node
`D1 via node L1.
`
`Routing data to D1 using IP addressing becomes prob-
`lematic when D1 moves outside of its home network 20,
`since node D1’s IP address does not automatically change to
`reflect its new location within a different network. As a
`
`consequence, all the data intended to be sent to node D1 will
`continue to be routed over the external network 12 to node
`
`A1. If node A1 does not have a separate connection to device
`D1 when data packets arrive, node A1 will either drop the
`data packets or queue them for retransmission on the
`assumption that D1 will establish a new connection with A1.
`Referring to FIG. 1, when D1 relocates to a position
`within the wireless coverage area of network 22 it listens to
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`US 6,891,820 B1
`
`5
`the connectivity information broadcast by the nodes within
`its range (device D1 is shown in phantom in network 22). If
`device D1 becomes located sufficiently near node L3, it may
`listen to its connectivity advertisement and determine a path
`over which data may be routed from node A1. After making
`this determination, D1 requests a connection to node A1 via
`a node along the chosen path (e.g., node L3). In order to
`establish a connection between nodes D1 and A1, node L3
`establishes a connection to node L2 which in turn establishes
`a connection to node A1. Once these connections have been
`made, node A1 will forward any data packets addressed to
`D1 that it has received over the hard-wired network 12.
`
`FIG. 2 depicts an alternate embodiment of the present
`invention in which a wireless node L2' exists as a member
`of both first and second wireless networks 20' and 22'. The
`node L2' facilitates internetworking between the networks
`20' and 22' in the manner described in the aforementioned
`copending Patent Application entitled “Distributed Manage-
`ment of an Extended Network Containing Short-Range
`Wireless Links”. The wireless node L2', or “internetworking
`node”, understands the protocols of both the first and second
`wireless networks 20' and 22' and is capable of transparently
`relaying data traffic therebetween.
`Referring again to FIG. 2, once device D1' begins moving
`outside of its home network 20' it may anticipate the loss of
`its connection to the network access node A1'. This is
`because device D1' monitors the signal strength of the
`advertisements being transmitted from L1', and will take
`notice when this signal strength drops below a predefined
`threshold. Once device D1' determines that a dropped con-
`nection between itself and node L1' is imminent,
`it will
`“listen” to the advertisements being broadcast by other
`wireless nodes within its range to determine if it can
`establish a simultaneous connection to node A1'. In the
`exemplary implementation of FIG. 2, device D1' determines
`that it may establish communication with node A1' via node
`L2‘. Accordingly, device D1' then drops its connection with
`L1' after establishing a connection with node L2'. In this way
`device D1' endeavors to minimize the risk of loss of data
`packets by briefly maintaining a simultaneous connection to
`two distinct wireless nodes. In applications where prevent-
`ing any loss of data packets is very important, device D1'
`may maintain such a simultaneous connection continuously
`or for substantially longer periods of time.
`FIG. 3 is a block diagram illustratively representing the
`components of a wireless node 100 and associated software
`configured in accordance with a preferred embodiment of
`the present invention. Referring to FIG. 3, the wireless node
`100 may be in the form of an electronic device (e. g., a laptop
`or desktop computer, hand-held electronic organizer, or
`printer) containing a first wireless adapter card 104 and a
`first RF transceiver 106 disposed for communication in
`accordance with a first network communication standard.
`The wireless node 100 may also optionally include a second
`wireless adapter card 108 and a second RF transceiver 110
`for communicating in accordance with a second network
`communication standard. The second wireless adapter card
`108 and the second RF transceiver 110 may be included
`within the wireless node 100 when,
`for example,
`it
`is
`anticipated that the wireless node may participate in net-
`works operative in accordance with different network stan-
`dards. For example, internetworking node L2' would pref-
`erably be configured with different wireless transceiver and
`associated adapter cards to the extent the first network 20'
`and second network 22' were governed by differing network
`communication standards. The wireless node 100 may also
`include a LAN adapter card 112 for facilitating communi-
`cation with a wired LAN, or alternately a wireline modem
`for effecting communication through the PSTN.
`Each wireless adapter card and transceiver is controlled
`by a CPU 114 operative to execute program instructions of
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`the various software routines 122 stored in memory 126.
`Within wireless nodes, a network resources table 130 is
`updated in response to internet management broadcasts by
`transmitting nodes of the individual wireless networks. The
`network resources table 130 stores the network address and
`services offered by each wireless node.
`In the case of
`internetworking node L2',
`these advertised services may
`include the services provided by a wireless node from a
`neighboring network in communication with the internet-
`working node.
`Included among the software routines 122 within inter-
`networking nodes is a forwarding routine 138 for forwarding
`messages to the wired LAN via the LAN adapter card 112,
`or to another wireless node via one of the wireless trans-
`ceivers 106, 110 and associated wireless adapter card 104,
`108. An advertisement generating routine 140 operates to
`generate the advertisements issued by the wireless node 100
`which specify its network address and services offered.
`Although the above application has been described pri-
`marily with reference to specific embodiments, one skilled
`in the art can readily appreciate that the teachings of the
`present invention may be applied in other communication
`contexts. For example, in certain embodiments the first and
`second wireless networks described above could instead
`comprise networks of fixed devices linked by hard-wired
`local area networks (“LANs”). Assuming a wireless or other
`communication link could be established between a pair of
`devices within the different networks, data could be for-
`warded among such networks in accordance with the inven-
`tion upon movement of a device from one network to the
`other. Thus the application is meant only to be limited by the
`scope of the appended claims.
`What is claimed is:
`
`1. A data communication system comprising:
`a first network including a first network access point and
`a first plurality of nodes;
`a second network including a second network access point
`and a second plurality of nodes; and
`means for forwarding, from said first network to said
`second network via a wireless internetwork path, mes-
`sage information received at said first network and
`addressed to a first wireless node of said first plurality
`of nodes when said first wireless node establishes
`communication with said second network wherein said
`wireless internetwork path includes one or more wire-
`less connections involving at least one of said first
`plurality of nodes and at
`least one of said second
`plurality of nodes to the exclusion of said first network
`access point and said second network access point.
`2. The data communication system of claim 1 wherein
`said wireless internetwork path includes an internetworking
`node included within said first plurality of nodes and within
`said second plurality of nodes.
`3. The data communication system of claim 2 wherein
`said internetworking node includes:
`means for receiving a first set of network information
`relating to said first network from said first plurality of
`nodes, said first set of network information identifying
`said first network access point wherein said message
`information is available from said first network access
`point; and
`means for transmitting, to one of said second plurality of
`nodes, said first set of network information and an
`identity of said internetworking node.
`4. The data communication system of claim 3 wherein
`said one of said second plurality of nodes includes means for
`broadcasting said first set of network information, said first
`wireless node including means for receiving said first set of
`network information broadcast by said one of said second
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`US 6,891,820 B1
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`7
`plurality of nodes upon establishing communication with
`said second network.
`5. The data communication system of claim 1 wherein
`said means for forwarding includes means for transmitting
`said message information over one of said wireless connec-
`tions.
`6. A data communication system comprising:
`a first network including a first plurality of wireless nodes,
`said first network having a first network access point
`for receiving message information directed to said first
`network;
`a second network including a second network access point
`and a second plurality of wireless nodes; and
`an internetworking node configured to forward portions of
`said message information addressed to one of said first
`plurality of wireless nodes via a wireless interconnec-
`tion path from said first network access point to said
`second network when said one of said first plurality of
`nodes establishes communication with said second
`network, said wireless internetwork path including one
`or more wireless connections involving at least one of
`said first plurality of wireless nodes and at least one of
`said second plurality of wireless nodes to the exclusion
`of said first network access point and said second
`network access point.
`7. A data communication system comprising:
`a first wireless network including a first network access
`point and a first plurality of wireless nodes, said first
`network access point providing a first IP address to a
`first wireless node of said first plurality of wireless
`nodes upon said first node joining said first wireless
`network;
`a second network including a second plurality of wireless
`nodes; and
`means for forwarding, from said first wireless network to
`said second wireless network via a wireless internet-
`work path, message information received at said first
`wireless network and addressed to said first IP address
`when said first wireless node establishes communica-
`tion with said second wireless network wherein said
`wireless internetwork path includes a wireless connec-
`tion between at
`least one of said first plurality of
`wireless nodes and at least one of said second plurality
`of wireless nodes to the exclusion of said first network
`access point and said second network access point and
`is defined based at least in part upon a connectivity
`advertisement broadcast by one of said second plurality
`of wireless nodes.
`8. The data communication system of claim 7 wherein
`said wireless internetwork path includes an internetworking
`node included within said first plurality of wireless nodes
`and within said second plurality of wireless nodes.
`9. The data communication system of claim 7 wherein
`said first wireless node is configured to determine said
`wireless internetwork path based upon said connectivity
`advertisement and an additional connectivity advertisement
`broadcast by one of said first plurality of wireless nodes.
`10. The data communication system of claim 1 wherein
`said first wireless node is configured to determine said
`wireless internetwork path based upon said connectivity
`advertisement and an additional connectivity advertisement
`broadcast by one of said second plurality of wireless nodes.
`11. A method of data communication comprising:
`broadcasting, from a first node of a first plurality nodes
`included within a first wireless network, a connectivity
`advertisement identifying its address and one or more
`additional addresses corresponding to other of said first
`plurality of nodes;
`determining a wireless internetwork path based at least in
`part upon said connectivity advertisement, said wire-
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`less internetwork path including one or more wireless
`connections involving at least one of said first plurality
`of nodes and at least one of a second plurality of nodes
`of a second wireless network wherein said one or more
`wireless connections are defined to the exclusion of a
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`first network access point associated with said first
`wireless network and a second network access point
`associated with said second wireless network; and
`forwarding, from said first wireless network to said sec-
`ond wireless network via said wireless internetwork
`
`path, message information received at said first net-
`work and addressed to said first node when said first
`node establishes communication with said second net-
`work.
`
`12. The method of claim 11 further including:
`receiving, at an internetworking nodes included within
`said first plurality of nodes and said one or more nodes
`of said second wireless network, a first set of network
`information relating to said first network from said first
`plurality of nodes, said first set of network information
`identifying said first network access point wherein said
`message information is available from said first net-
`work access point; and
`transmitting, to one of said one of more nodes of said
`second wireless network, said first set of network
`information and an identity of said internetworking
`node.
`
`including
`13. The method of claim 12 further
`broadcasting, from said one of said second plurality of
`nodes, said first set of network information and receiving, at
`said first node, said first set of network information broad-
`cast by said one of said second plurality of nodes upon
`establishing communication with said second network.
`14. A method for data communication comprising:
`receiving, at a first wireless node of a first plurality of
`wireless nodes of a first wireless network, a first IP
`address upon association of said first wireless node
`with said first wireless network;
`terminating, at said first wireless node, a first network
`connection with said first wireless network and estab-
`lishing a second network connection with a second
`wireless network upon determining at said first wireless
`node that signal strength over said first network con-
`nection has become less than a minimum threshold;
`defining, at said first wireless node, a wireless internet-
`work path including one or more wireless connections
`involving at least one of said first plurality of wireless
`nodes and at least one of a second plurality of wireless
`nodes of said second wireless network wherein said one
`or more wireless connections are defined to the exclu-
`sion of a first network access point of said first wireless
`network and a second network access point of said
`second wireless network; and
`receiving, at said first wireless node, message information
`forwarded from said first wireless network to said
`second wireless network via said wireless internetwork
`path, said message information being previous